Selective plasma amino acids (glycine, serine, glutamate and tryptophan) will be lower in drug-free patients w/schizophrenia compared to normal controls. Plasma 5-hydroxyindolacetic acid/homovanillic acid ratio will predict treatment response and side effects of the antipsychotic drug treatment. Basal plasma cortisol levels will be lower in patients w/schizophrenia compared to normal controls and treatment w/atypical antipsychotic drug will normalize basal plasma cortisol levels.